Laminated electronic component and manufacturing method therefor

ABSTRACT

A method for manufacturing a laminated electronic component in which, when first plating layers that respectively connect a plurality of internal electrodes to each other and second plating layers that improves the mountability of a laminated electronic component are formed as external terminal electrodes, the entire component main body is treated with a water repellent agent after the formation of the first plating layers, and the water repellent agent on the first plating layers is then removed before the formation of the second plating layers. The gaps between the end edges of the first plating films on the outer surface of the component main body and the outer surface of the component main body are filled with the water repellent agent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a laminated electronic component and amethod for manufacturing the laminated electronic component, and moreparticularly, to a laminated electronic component including a platedexternal terminal electrode plated directly on the laminated electroniccomponent so as to be electrically connected to a plurality of internalelectrodes, and a method for manufacturing the laminated electroniccomponent.

2. Description of the Related Art

As shown in FIG. 5, a laminated electronic component 101 defining alaminated ceramic capacitor is typically provided with a component mainbody 105 which includes a stacked structure including a plurality ofstacked insulator layers 102 made of, for example, a dielectric ceramicand a plurality of layered internal electrodes 103 and 104 disposedalong the interfaces between the insulator layers 102. The respectiveends of the plurality of internal electrodes 103 and the plurality ofinternal electrodes 104 are respectively exposed at opposite endsurfaces 106 and 107 of the component main body 105, and externalterminal electrodes 108 and 109 are arranged so as to electricallyconnect the respective ends of the internal electrodes 103 to each otherand electrically connect the respective ends of the internal electrodes104 to each other.

For the formation of the external terminal electrodes 108 and 109,typically, a metal paste including a metal component and a glasscomponent is applied onto the end surfaces 106 and 107 of the componentmain body 105, and then fired, thereby forming a paste electrode layer110. Next, a first plating layer 111 including, for example, nickel asits main component is formed on the paste electrode layer 110, and asecond plating layer 112 including, for example, tin or gold as its maincomponent is formed on the first plating layer 112. More specifically,each of the external terminal electrodes 108 and 109 includes athree-layer structure of the paste electrode layer 110, the firstplating layer 111, and the second plating layer 112.

The external terminal electrodes 108 and 109 are required to havefavorable solderability when the laminated electronic component 101 ismounted on a substrate via solder. At the same time, the externalterminal electrode 108 is required to have the function of electricallyconnecting the plurality of internal electrodes 103 to each other, whichare electrically insulated from each other, and the external terminalelectrode 109 is required to have the function of electricallyconnecting the plurality of internal electrodes 104 to each other, whichare electrically insulated from each other. The second plating layers112 ensure the solderability and the paste electrode layers 110electrically connect the internal electrodes 103 to each other and theinternal electrodes 104 to each other. The first plating layers 111prevent solder erosion in the solder joint.

However, the paste electrode layer 110 has a large thickness, fromseveral tens of μm to several hundreds of μm. Therefore, in order tolimit the dimensions of the laminated electronic component 101 tocertain specifications, the effective volume for providing a capacitancemust be reduced because the thickness and volume of the paste electrodelayers 110. On the other hand, the plating layers 111 and 112 have athickness of only several μm. Thus, if the external terminal electrodes108 and 109 can be defined by only the first plating layers 111 and thesecond plating layers 112, the effective volume for providing thecapacitance can be increased.

For example, Japanese Unexamined Patent Publication No. 2004-146401discloses a method in which a conductive paste is applied along at leastridge sections of end surfaces of a component main body in the directionof stacking internal electrodes so as to come into contact with leadingsections of the internal electrodes, and the conductive paste is firedor thermally cured to form a conductive paste. Further, the end surfacesof the component main body are subjected to electroplating, therebyforming an electroplating film so as to be connected to the conductivefilm on the ridge sections described above. According to this method,the thickness of the external terminal electrodes at the end surfacescan be reduced.

In addition, Japanese Unexamined Patent Publication No. 63-169014discloses a method in which a conductive metal film is deposited byelectroless plating on the entire sidewall surface of a component mainbody, at which internal electrodes are exposed, so as to short circuitthe internal electrodes exposed at the sidewall surface.

However, in the methods for forming external terminal electrodes asdescribed in Japanese Unexamined Patent Publications No. 2004-146401 andNo. 63-169014, plating is performed directly on the ends at which theinternal electrodes are exposed. Thus, a plating solution is likely toenter the component main body along the interfaces between the internalelectrodes and the insulator layers and may erode the ceramic definingthe insulator layers and the internal electrodes, thereby causingstructural defects. Furthermore, this results in defects in terms ofreliability, such as degraded load characteristics against humidity forthe laminated electronic component.

In particular, when tin or gold plating is to be applied, the problemsdescribed above are more likely to be caused because a tin or goldplating solution generally contains a highly corrosive complexing agent.

In order to solve the problems described above, for example, theInternational Publication No. WO2007/119281 discloses providing a waterrepellent agent on end surfaces of a component main body at whichrespective ends of internal electrodes are exposed, in order to fill thegaps at the interfaces between insulator layers and the internalelectrodes with this water repellent agent, and then forming platinglayers as bases of external terminal electrodes onto the end surfaces.Such a water repellent agent improves the lifetime characteristics in aload test against humidity.

However, the technique described in International Publication No.WO2007/119281 has the following problems.

The water repellent agent is likely to adhere to the ceramic sectionsdefining the insulator layers, rather than the metal sections definingthe internal electrodes. If the distance between the internal electrodesis large (that is, when the insulator layers are thick and when thenumber of stacked internal electrodes is small), most of the endsurfaces at which the respective ends of the internal electrodes areexposed will be covered with the water repellent agent, which decreasesthe ability to deposit plating onto the end surfaces at which theinternal electrodes are exposed.

In addition, in order to improve the fixing strength of the externalterminal electrodes to the component main body, a heat treatment may beperformed at a temperature of about 800° C. or more after the formationof the plating layers as bases. However, such a heat treatment willcause the water repellent agent to disappear.

It is to be noted that, for example, Japanese Unexamined PatentPublication No. 2002-289465 discloses providing a water repellent agentbefore a plating process when forming paste electrode layers by firingand then performing plating as in the prior art described with referenceto FIG. 5, rather than forming external terminal electrodessubstantially only by plating. The paste electrode layers formed byfiring are not only formed on end surfaces of a component main body inthe shape of a rectangular parallelepiped, at which respective ends ofinternal electrodes are exposed, but also formed so that the end edgesof the paste electrode layers are located on the principal surfaces andside surfaces adjacent to the end surfaces.

However, the technique described in Japanese Unexamined PatentPublication No. 2002-289465 above encounters the following problem.Moisture is likely to enter from the gaps between the end edges of thepaste electrode layers formed by firing and the component main bodybecause segregation of a glass component is likely to occur in thissection of the gaps and the glass is easily dissolved by the platingsolution even if the glass is coated with the water repellent agent.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of thepresent invention provide a method for manufacturing a laminatedelectronic component and a laminated electronic component manufacturedin accordance with the manufacturing method described above.

A method for manufacturing a laminated electronic component according toa preferred embodiment of the present invention includes the steps ofpreparing a component main body having a stacked structure and includinga plurality of internal electrodes formed therein and each of theinternal electrodes being partially exposed, and forming an externalterminal electrode on an outer surface of the component main body, theexternal terminal electrode electrically connected to the internalelectrodes. In order to solve the technical problems described above,the step of forming the external terminal electrode preferably includesa step of forming a first plating layer on the exposed surfaces of theinternal electrodes in the component main body, a step of applying awater repellent agent at least onto a surface of the first plating layerand onto a section on the outer surface of the component main body, thesection including an end edge of the first plating layer, a step ofremoving the water repellent agent applied onto the surface of the firstplating layer, and then a step of forming a second plating layer on thefirst plating layer.

The step of forming the external terminal electrode preferably furtherincludes a step of applying a heat treatment to the component main bodywith the first plating layer formed thereon between the step of formingthe first plating layer and the step of applying the water repellentagent.

Preferably, the step of forming the first plating layer includes a stepof forming a plating layer including copper, for example, as its maincomponent, and the step of forming the second plating layer includes astep of forming a plating layer including nickel, for example, as itsmain component and a subsequently performed step of forming a platinglayer including tin or gold, for example, as its main component.

A laminated electronic component according to another preferredembodiment of the present invention includes a component main bodyhaving a stack structure and including a plurality of internalelectrodes disposed therein, each of the internal electrodes beingpartially exposed, and an external terminal electrode electricallyconnected to the internal electrode and provided on an outer surface ofthe component main body. The external terminal electrode preferablyincludes a first plating layer provided on the exposed surfaces of theinternal electrodes in the component main body, and a second platinglayer provided on the first plating layer, and further preferablyincludes a water repellent agent filling a gap between an end edge ofthe first plating film on the outer surface of the component main bodyand the outer surface of the component main body.

In the laminated electronic component according to a preferredembodiment of the present invention, an interdiffusion layer ispreferably provided in a region having a length of about 2 μm or more,for example, from a boundary between the internal electrode and thefirst plating layer.

Preferably, the first plating layer includes a plating layer includingcopper, for example, as its main component, and the second plating layerincludes a plating layer including nickel, for example, as its maincomponent, and a plating layer provided thereon including tin or gold,for example, as its main component.

Preferred embodiments of the present invention are particularlyadvantageously applied when the component main body has a substantiallyrectangular parallelepiped shape, for example, including a pair ofprincipal surfaces opposed to each other, a pair of side surfacesopposed to each other, and a pair of end surfaces opposed to each other,the end surfaces serving as the exposed surfaces of the internalelectrodes, and when the first plating layer is disposed on the endsurfaces and such that end edges of the first plating layer are locatedon the principal surfaces and the side surfaces, which are adjacent tothe end surfaces.

According to a preferred embodiment of the present invention, before theformation of the second plating layer after the formation of the firstplating layer, the water repellent agent is applied, and the waterrepellent agent applied onto the surface of the first plating layer isremoved. In this case, the water repellent agent remains so as to fillthe gap between the end edge of the first plating layer on the outersurface of the component main body and the outer surface of thecomponent main body.

Therefore, when the first plating layer is arranged to electricallyconnect the plurality of internal electrodes to each other, whereas thesecond plating layer is arranged to improve the mountability of thelaminated electronic component, the water repellent agent is appliedbefore the formation of the plating layer arranged to improve themountability. Accordingly, a highly corrosive complexing agent used in aplating solution for, for example, tin plating or gold plating whichimprove the mountability is prevented from entering the inside of thecomponent main body from the gap between the end edge of the firstplating layer and the component main body, thereby effectively andsufficiently ensuring the reliability of the laminated electroniccomponent.

In addition, the water repellent agent effectively prevents ingress ofmoisture from the gap between end edge of the first plating layer andthe component main body. For example, in the case of the component mainbody having a substantially rectangular parallelepiped shape, when thefirst plating layer is formed on the end surface of the component mainbody such that the end edge of the first plating layer is located on theprincipal surface and side surface adjacent to the end surface, ingressof moisture is effectively prevented from the gap between the end edgeof the first plating layer and the principal surface and side surface.This prevention of moisture ingress effectively and reliably improvesthe reliability of the laminated electronic component.

In addition, since the water repellent agent applied onto the surface ofthe first plating layer is removed before the formation of the secondplating layer as described above, a condition is provided in whichalmost no water repellent agent is present on the surface of the firstplating layer. Therefore, the problem of difficulty in depositing aplating film is less likely to be caused in the formation of the secondplating layer. Furthermore, this enables the use of an agent havingstrong water repellency as the water repellent agent, thereby furtherimproving the reliability.

When the component main body including the first plating layer formedthereon is subjected to a heat treatment between the step of forming thefirst plating layer and the step of applying the water repellent agent,the above-described problem of moisture ingress is more effectively andreliably prevented. In addition, the problem of disappearance of thewater repellent agent due to the heat treatment does not occur.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a laminated electroniccomponent 1 manufactured in accordance with a manufacturing methodaccording to a preferred embodiment of the present invention, which alsoshows an enlarged portion of the laminated electronic component 1.

FIG. 2 is an enlarged cross-sectional view illustrating a section of acomponent main body 2 provided with a first plating layer 10 formedthereon and then subjected to a thermal treatment for the purpose offorming an external terminal electrode 8, in the manufacturing processof the laminated electronic component 1 shown in FIG. 1.

FIG. 3 is a cross-sectional view illustrating the component main body 2with a water repellent agent applied thereto, in the manufacturingprocess of the laminated electronic component 1 shown in FIG. 1.

FIG. 4 is a cross-sectional view illustrating the component main body 2with the water repellent agent removed, in the manufacturing process ofthe laminated electronic component 1 shown in FIG. 1, which also showsan enlarged portion of the laminated electronic component 1.

FIG. 5 is a cross-sectional view of a conventional laminated electroniccomponent 101.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a method for manufacturing a laminated electronic component accordingto a preferred embodiment of the present invention, the formation ofexternal terminal electrodes is preferably performed by direct platingonto exposed end surfaces of internal electrodes in a component mainbody, without forming any paste electrodes, sputtered electrodes,deposited electrodes, or other types of electrodes. Further, the platingfilm preferably includes at least two layers, and more preferably,includes a first plating layer which electrically connects a pluralityof internal electrodes to each other and a second plating layer whichimproves the mountability of the laminated electronic component.According to a preferred embodiment of the present invention, after theformation of the first plating layer, a water repellent agent is appliedat least onto the surface of the first plating layer and onto a sectionon the outer surface of the component main body at which an end edge ofthe first plating layer is located, and before the formation of thesecond plating layer, the water repellent agent applied onto the surfaceof the first plating layer is removed. FIG. 1 shows an example of thelaminated electronic component.

Referring to FIG. 1, a laminated electronic component 1 includes acomponent main body 2 having a stack structure. The component main body2 includes a plurality of internal electrodes 3 and 4 disposed therein.More specifically, the component main body 2 includes a plurality ofstacked electrically insulating insulator layers 5 and a plurality oflayered internal electrodes 3 and 4 arranged along the interfacesbetween the insulator layers 5.

When the laminated electronic component 1 defines a laminated ceramiccapacitor, the insulator layers 5 are preferably made of a dielectricceramic, for example. It is to be noted that the laminated electroniccomponent 1 may define other elements such as an inductor, a thermistor,or a piezoelectric component, for example. Therefore, depending on thefunction of the laminated electronic component 1, the insulator layers 5may preferably be made of a magnetic ceramic, a semiconductor ceramic, apiezoelectric ceramic, or other suitable material or may be made of amaterial including a resin, for example, instead of a dielectricceramic.

The respective ends of the plurality of internal electrodes 3 and theplurality of internal electrodes 4 are exposed at two end surfaces 6 and7 of the component main body 2, and external terminal electrodes 8 and 9are respectively arranged so as to electrically connect the respectiveends of the internal electrodes 3 to each other and electrically connectthe respective ends of the internal electrodes 4 to each other.

It is to be noted that while the laminated electronic component 1 shownin FIG. 1 is preferably a two-terminal type component including the twoexternal terminal electrodes 8 and 9, the present invention can also beapplied to multi-terminal type laminated electronic components.

The respective external terminal electrodes 8 and 9 preferably includefirst plating layers 10 and 11 formed by plating directly on the exposedsurfaces of the internal electrodes 3 and 4 in the component main body2, that is, on the end surfaces 6 and 7, and second plating layers 12and 13 formed on the first plating layers 10 and 11, respectively.

The first plating layers 10 and 11 are provided to electrically connectthe plurality of internal electrodes 3 and 4 to each other, and arepreferably made of a plating layer including copper, for example, as itsmain component. On the other hand, the second plating layers 12 and 13are provided to improve the mountability of the laminated electroniccomponent 1, and preferably respectively include solder barrier layers14 and 15 made of a plating layer including, for example, nickel as itsmain component, and solderability providing layers 16 and 17 preferablymade of a plating layer including, for example, tin or gold as its maincomponent, which are formed on the solder barrier layers 14 and 15 so asto provide solderability. It is to be noted that the plating includingtin as its main component also preferably includes, for example, Sn—Pbsolder plating. In addition, the plating including nickel as its maincomponent also preferably includes Ni—P plating by electroless plating.

When the first plating layers 10 and 11 are made of a plating layerincluding copper as its main component as described above, the favorablethrowing power of copper improves the efficiency of the plating processand increases the fixing strength of the external terminal electrodes 8and 9. However, the first plating layers 10 and 11 may be made ofnickel, for example, and the second plating layers 12 and 13 may be madeof tin or gold, for example.

The plating method for forming the first plating layers 10 and 11 andthe second plating layers 12 and 13 may be an electroless plating methodof depositing metal ions with the use of a reducing agent, or may be anelectroplating method through an electrifying process, for example.

In FIG. 1, regarding a section A on the outer surface of the componentmain body 2 at which edges of the first plating films 10 and 11 arelocated, an enlarged portion of the section A is shown in which the endedge of the first plating film 10 is located. It is to be noted that thesection A in which the end edge of the second plating film 11 is locatedis also substantially the same as the enlarged and shown section A inwhich the end edge of the first plating film 10 is located.

The gaps between the end edges of the first plating films 10 and 11 onthe outer surface of the component main body 2 and the outer surface ofthe component main body 2 are filled with a water repellent agent 18.While the type of the water repellent agent 18 is not particularlylimited as long as the water repellent agent 18 prevents ingress of aplating solution or moisture, for example, a silane coupling agent ispreferred.

Next, a method for manufacturing the laminated electronic component 1shown in FIG. 1, and in particular, a method for forming the externalterminal electrodes 8 and 9 will be described.

First, the component main body 2 is prepared by a known method. Next,the external terminal electrodes 8 and 9 are formed respectively on theend surfaces 6 and 7 of the component main body 2 to electricallyconnect the internal electrodes 3 and 4 to each other.

For the formation of the external terminal electrodes 8 and 9, the firstplating layers 10 and 11 are first formed on the end surfaces 6 and 7 ofthe component main body 2. In the component main body 2 before platingis applied, the plurality of internal electrodes 3 exposed at the oneend surface 6 are electrically insulated from each other and theplurality of internal electrodes 4 exposed at the other end surface 7are electrically insulated from each other. In order to form the firstplating layers 10 and 11, metal ions in a plating solution are firstdeposited onto the exposed sections of each of the internal electrodes 3and 4. Then, the plated deposits are further grown to physically connectthe plated deposits on the respective exposed sections of the adjacentinternal electrodes 3 to each other and the plated deposits on therespective exposed sections of the adjacent internal electrodes 4 toeach other. In this manner, uniform and dense first plating layers 10and 11 are formed.

In this preferred embodiment, the component main body 2 of the laminatedelectronic component 1 preferably has a substantially rectangularparallelepiped shape, for example, which includes a pair of principalsurfaces 19 and 20 opposed to each other and a pair of side surfacesopposed to each other (not shown in FIG. 1) in addition to the pair ofend surfaces 6 and 7 described above. Further, the first plating layers10 and 11 are preferably formed on the pair of end surfaces 6 and 7,respectively, such that the end edges of the first plating layers 10 and11 are located on the pair of principal surfaces 19 and 20 and the pairof side surfaces, which are adjacent to the end surfaces 6 and 7.

In order to enable the first plating layers 10 and 11 to be formedefficiently such that the end edges of the first plating layers 10 and11 extend to the pair of principal surfaces 19 and 20 and the pair ofside surfaces, as described above, internal dummy conductors 21 and 22are preferably formed in an outer layer section of the component mainbody 2 so as to be exposed at the end surfaces 6 and 7. Furthermore,although not shown in the figure, external dummy conductors maypreferably be formed on ends of the principal surfaces 19 and 20 of thecomponent main body 2, which are adjacent to the end surfaces 6 and 7.The internal dummy conductors 21 and 22 and external dummy conductors donot substantially contribute to the development of electricalcharacteristics, but facilitate the deposition of metal ions for theformation of the first plating layers 10 and 11 improve the platinggrowth.

Furthermore, in order to adequately expose the internal electrodes 3 and4 and the internal dummy conductors 21 and 22 at the end surfaces 6 and7 before the plating step described above, it is preferable to performpolishing on the end surfaces 6 and 7 of the component main body 2. Inthis case, when polishing is performed to the extent that the respectiveexposed ends of the internal electrodes 3 and 4 and the internal dummyconductors 21 and 22 project from the end surfaces 6 and 7, therespective exposed ends will be spread in a planar direction, therebyreducing the energy required for the plating growth.

Next, the component main body 2 including the first plating layers 10and 11 formed as described above is preferably subjected to a heattreatment. A heat treatment temperature, for example, of preferablyabout 600° C. or more, and more preferably about 800° C. or more isused. The state after this heat treatment is shown in FIG. 2. FIG. 2shows the internal electrode 3 and the first plating layer 10. Thestructure on the internal electrode 4 and the first plating layer 11,not shown in FIG. 2, is substantially the same as the structure of theinternal electrode 3 and the first plating layer 10, shown in FIG. 2,and the description thereof will be omitted accordingly.

Referring to FIG. 2, an interdiffusion layer 25 is formed between theinternal electrode 3 and the first plating layer 10. The interdiffusionlayer 25 is preferably present in a region with a length L of about 2 μmor more, for example, from the boundary between the internal electrode 3and the first plating layer 10. In other words, the heat treatment ispreferably performed under a condition such that the length L is about 2μm or more, for example. The formation of such an interdiffusion layer25 more effectively and reliably prevents the moisture from entering theinside of the component main body 2.

Next, the step described above of applying a water repellent agent 18 isperformed. It is sufficient to apply the water repellent agent 18 atleast onto the surfaces of the first plating layers 10 and 11 and onto asection of the external surface of the component main body 2 in whichrespective end edges of the first plating layers 10 and 11 are located.However, in this preferred embodiment, the water repellent agent 18 ispreferably applied onto the entire surface of the component main body 2with the first plating layers 10 and 11 formed thereon, as shown in FIG.3, since the method of immersing the component main body 2 in a liquidincluding the water repellent agent 18 is preferably used to apply thewater repellent agent 18. It is to be noted that other methods, such asa spraying method, for example, may be used to apply the water repellentagent 18.

Due to the shape of the outer surface of the component main body 2 withthe first plating layers 10 and 11 formed thereon, the surface tensionof the water repellent agent 18, and other factors, the water repellentagent 18 adheres onto the first plating layers 10 and 11 to form arelatively thin and uniform film and the water repellent agent 18adheres to the section A on the principal surfaces 19 and 20 and sidesurfaces of the component main body 2 at which the end edges of thefirst plating layers 10 and 11 are located to form a relatively thickfilm. It is to be noted that while the film of the water repellent agent18 is shown with a thickness that is exaggerated in FIG. 3, it should beunderstood that the thickness as shown in the figure is not actuallyachieved.

In addition, when a silane coupling agent is used as the water repellentagent 18 as described above, the silane coupling agent preferentiallyadheres to the ceramic surface because the silane coupling agent isstrongly bonded to OH groups. On the other hand, a thin and uniformnatural oxidation film is present on the surfaces of the first platinglayers 10 and 11, thus enabling the water repellent agent 18 to beformed uniformly in a thin film on the natural oxidation film. This alsocontributes to the adherence of the water repellent agent 18 asdescribed above.

Next, the water repellent agent 18 applied onto the surfaces of thefirst plating layers 10 and 11 is removed. For the removal of the waterrepellent agent 18, for example, the component main body 2 with thefirst plating layers 10 and 11 formed is preferably immersed in asolvent which is capable of dissolving the water repellent agent 18, orthe solvent is sprayed onto the entire surface of the component mainbody 2 with the first plating layers 10 and 11 formed. As a result ofthis step, as shown in an enlarged section in FIG. 4, the waterrepellent agent 18 is not completely removed and a portion remains so asto fill the gaps between the end edges of the first plating layers 10and 11 on the principal surfaces 19 and 20 and side surfaces of thecomponent main body 2, and the component main body 2. On the other hand,the water repellent agent 18 on the first plating layers 10 and 11 andon the exposed section of the principal surfaces 19 and 20 and sidesurfaces of the component main body is substantially entirely removed.

As described above, the water repellent agent 18 preferably remains onlyin the gaps, and it is thus not necessary to perform any additionalprocess such as, for example, selectively spraying a solvent to thesection other than the section A.

The water repellent agent 18 effectively prevents ingress of moisturefrom the gaps between the end edges of the first plating layers 10 and11 and the principal surfaces 19 and 20 and side surfaces.

Next, the second plating layers 12 and 13 are formed. The second platinglayers 12 and 13 are formed after the formation of the first platinglayers 10 and 11, and thus, can be easily formed using a normal method.This is because locations to be plated have a conductive and continuoussurface when the second plating layers 12 and 13 are formed.

In addition, since the water repellent agent 18 applied on the surfacesof the first plating layers 10 and 11 is removed, there is almost nowater repellent agent 18 on the surfaces of the first plating layers 10and 11. Therefore, during the formation of the second plating layers 12and 13, the problem of deposition of a plating film being inhibited bythe water repellent agent 18 is prevented. Furthermore, this enables theuse of an agent having a strong water repellency as the water repellentagent 18, thereby contributing to further improvement in reliability.

In a preferred embodiment of the present invention, in order to form thesecond plating layers 12 and 13, the step of forming the solder barrierlayers 14 and 15 preferably made of, for example, nickel, and the stepof forming the solderability providing layers 16 and 17 preferably madeof, for example, tin or gold, are sequentially performed.

Next, an experimental example will be described, which was performed toconfirm the advantageous effects of preferred embodiments of the presentinvention.

In this experimental example, laminated ceramic capacitors as sampleswere manufactured in accordance with the following steps.

(1) Preparation of Component Main Body

(2) Electrolytic Copper Plating

(3) Heat Treatment

(4) Application and Removal of Water Repellent Agent

(5) Electrolytic Nickel Plating

(6) Electrolytic Tin Plating

It is to be noted that cleaning with pure water was performed after eachof the plating steps (2), (5), and (6).

The details of each of the steps (1) to (6) are described below.

(1) Preparation of Component Main Body

A component main body having a length of about 0.94 mm, a width of about0.47 mm, and a height of about 0.47 mm defining a laminated ceramiccapacitor was prepared in which insulator layers were made of a bariumtitanate based dielectric ceramic, internal electrodes included nickelas their main component, the insulator layer between the adjacentinternal electrodes had a thickness of about 1.5 μm, and the number ofthe laminated internal electrodes was about 220. Furthermore, thiscomponent main body was provided with internal dummy conductors andexternal dummy conductors.

(2) Electrolytic Copper Plating

As plating baths, a copper strike bath shown in Table 1 below and athick copper bath shown in Table 2 were prepared.

TABLE 1 Copper Strike Bath Plating Bath Copper pyrophosphate 14 g/literPyrophosphoric acid 120 g/liter  Potassium oxalate 10 g/liter PH 8.7Bath Temperature 25° C.

TABLE 2 Thick Copper Bath Pyro-Bright Process from C. Uyemura & Co.,Ltd. Plating Bath pH 8.6 Bath Temperature 55° C.

Into a 300 ml horizontal rotating barrel, about 500 pieces of thecomponent main bodies were input, and in addition, about 100 ml ofconductive media having a diameter of about 0.7 mm was input. Then, thehorizontal rotating barrel was immersed in the copper strike bath shownin Table 1, and a current was applied at a current density of about 0.10A/dm² while rotating the horizontal rotating barrel at a barrelperipheral velocity of about 2.6 m/minute, thereby performing copperstrike plating until a film thickness of about 1 μm was obtained.

Then, the same horizontal rotating barrel was immersed in the thickcopper bath shown in Table 2, and a current was applied at a currentdensity of about 0.30 A/dm² while rotating the horizontal rotatingbarrel at the same barrel peripheral velocity, thereby carrying outthick copper plating until a film thickness of about 5 μm was obtained.

(3) Heat Treatment

The component main body including the copper plating layer formedthereon as described above was subjected to a heat treatment at atemperature of about 800° C. for about 5 minutes.

(4) Application and Removal of Water Repellent Agent

Next, the component main body subjected to the heat treatment wasimmersed in a liquid including a water repellent agent as shown in Table3 under reduced pressure for about 60 minutes, and then dried at about105° C. for about 15 minutes and then about 180° C. for about 1 minuteto apply the water repellent agent.

Next, as shown in Table 3, except for the specific samples, the sampleswere immersed in IPA (isopropyl alcohol) for 5 minutes to carry out astep of removing the water repellent agent.

TABLE 3 Sample No. Water Repellent Agent Removal Step 1 A.WR (NICCACHEMICAL CO., Yes LTD.) Stock Solution 2 A.PC (NICCA CHEMICAL CO., YesLTD.) Stock Solution 3 A.WR (NICCA CHEMICAL CO., No LTD.) Stock Solution4 A.PC (NICCA CHEMICAL CO., No LTD.) Stock Solution 5 Solution of A-WR(NICCA No CHEMICAL CO., LTD.) diluted with IPA to 3 weight % 6 Waterrepellent agent for Sample 1, applied after tin plating 7 Not Treated —

For sample 6 in Table 3, the water repellent agent for sample 1 wasused, and applied after the tin plating described below, rather thanafter the copper plating described above.

(5) Electrolytic Nickel Plating

Next, a Watts bath (weakly acid nickel bath) was used and set at atemperature of about 60° C. and pH about 4.2 to perform electroplatingat a current density of about 0.20 A/dm² for about 60 minutes, therebyforming a nickel plating layer having a thickness of about 4 μm on thecopper plating layer.

(6) Electrolytic Tin Plating

Next, NB-RZS from Ishihara Chemical Co., Ltd. was used as a plating bathand set at a temperature of about 30° C. and pH about 4.5 to performelectroplating at a current density of about 0.10 A/dm² for about 60minutes, thereby forming a tin plating layer having a thickness of about4 μm on the nickel plating layer.

A humidity-proof reliability test (temperature: about 125° C., relativehumidity: about 95%, applied voltage: about 6.3 V) was performed on thesamples. Then, when the insulation resistance for each case of after alapse of about 144 hours and after a lapse of about 288 hours was about1 MΩ or less, the sample was regarded as a defective, thereby obtainingthe number of defective samples with respect to the number of samples of70. The results are shown respectively as “The Number of Defectives inReliability Test (144 hours)” and “The Number of Defectives inReliability Test (288 hours)” in Table 4.

In addition, the plated surface after the step of (5) ElectrolyticNickel Plating was observed by a microscope to evaluate the nickelplating property. When the underlying copper was observed even if onlyslightly, the sample was regarded as a defective, thereby obtaining thenumber of defectives with respect to the number of samples of 70. Theresults are shown as “The Number of Defectives in Ni Plating”.

TABLE 4 The Number of The Number of Defectives in Defectives inReliability Reliability Ni (Plating) Test (144 Test (288 The Number ofSample No. hours) hours) Defectives 1 0 0 0 2 0 0 0 3 70 70 70 4 70 7070 5 0 5 0 6 14 28 0 7 18 42 0

In Tables 3 and 4, samples 1 and 2 are examples within the scope of thepresent invention, whereas samples 3 to 7 are comparative examplesoutside the scope of the present invention.

First, for samples 3 and 4, while the strong water repellent agents wereused as rough stock solutions, the removal steps for these waterrepellent agents were not performed. Thus, samples having defectiveplating were produced, and defective samples were also produced in thereliability test for a relatively short period of time of about 144hours.

For sample 5, the diluted water repellent agent was used. Thus, evenwithout performing the removal step for the water repellent agent, nodefective sample was produced in the reliability test for a relativelyshort period of time of about 144 hours, whereas defective samples wereproduced in the reliability test for a relatively long period of time ofabout 288 hours.

For sample 6, sealing by the water repellent agent was not sufficientfor the gaps between the end edges of the copper plating layers locatedon the principal surfaces and side surfaces of the component main bodyand the outer surface of the component main body, and defective sampleswere produced in the reliability tests.

For sample 7, the water repellent agent itself was not used. Thus, theresults were inferior in terms of reliability, even as compared tosample 6.

In contrast to these samples, for samples 1 and 2, while the strongwater repellent agents were used as rough stock solutions, the removalsteps for these water repellent agents were performed. Thus, no platingdefects were caused, and no defective samples were produced, not only inthe reliability test for about 144 hours, but also in the reliabilitytest for a relatively long period of time of about 288 hours.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing the scope andspirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A laminated electronic component comprising: acomponent main body having a stack structure and including a pluralityof internal electrodes provided therein, each of the plurality ofinternal electrodes including exposed surfaces; and an external terminalelectrode electrically connected to the plurality of internal electrodesand disposed on an outer surface of the component main body; wherein theexternal terminal electrode includes a first plating layer provideddirectly on the exposed surfaces of the plurality of internal electrodesin the component main body, and a second plating layer provided on thefirst plating layer; and a water repellent agent filled in a gap betweenan end edge of the first plating film on the outer surface of thecomponent main body and a section of the outer surface of the componentmain body on which the end edge of the first plating layer is located.2. The laminated electronic component according to claim 1, wherein aninterdiffusion layer is provided in a region with a length of about 2 μmor more from a boundary between the internal electrode and the firstplating layer.
 3. The laminated electronic component according to claim1, wherein the first plating layer includes a plating layer includingcopper as its main component, and the second plating layer includes aplating layer including nickel as its main component, and furthercomprising a plating layer including tin or gold as its main componentdisposed on the second plating layer.
 4. The laminated electroniccomponent according to claim 1, wherein the component main body has asubstantially rectangular parallelepiped shape including a pair ofprincipal surfaces opposed to each other, a pair of side surfacesopposed to each other, and a pair of end surfaces opposed to each other,the end surfaces serving as the exposed surfaces of the internalelectrodes, and the first plating layer is provided on the pair endsurfaces, and arranged so that end edges of the first plating layer aredisposed on the pair principal surfaces and the pair of side surfaces,which are adjacent to the pair of end surfaces.